1. Field of Invention
The invention relates to a hybrid driving device that employs an engine and an electric motor for a power source. In particular, the invention relates to a placement structure of a parking mechanism in a hybrid driving device that transmits power from the engine and the electric motor to the wheels through a countershaft.
2. Description of Related Art
A hybrid driving device, which uses, as a power source, a combustion engine (which will be referred to as the engine in this specification), an electric motor, and a generator used in combination with an electric motor, transmits power from a plurality of systems to wheels which allows it to take a variety of power train configurations. Japanese Patent Application Laid-Open Publication No. HEI 8-183347 discloses a driving device with a placement configuration that establishes any given gear ratio to transmit the output from an engine and the output from an electric motor and a generator, respectively, to a differential device. In this driving device, in an attempt to make the axial length of the mechanism shorter, an end of the countershaft on the side of the electric motor, which substantially affects the overall axial length of the device, is placed between each of the coil ends of the generator and the electric motor so that a part of the countershaft overlaps the generator and the electric motor in terms of the axial direction relationship.
The driving device is provided, as a parking device that restricts the rotation of wheels, with a parking mechanism that locks a parking gear built into a power transmission path by bringing the parking mechanism into engagement with a parking pole. In the related-art driving device, the parking gear of the parking mechanism is placed between a driven gear (a third gear) and a differential drive pinion gear (a fourth gear) on the countershaft.
A drive plate, that functions as a flywheel and a damper device indispensable to a connection to the engine, an electric motor and a countershaft, forms the three component elements that affects the overall axial length of a hybrid driving device, apart from the engine. Among them, the countershaft is the major factor that determines the axial length of the driving device.
Looking at the hybrid driving device of the related art with special emphasis on the countershaft, the rear end of the countershaft is configured to overlap the coil end of the electric motor in the axial direction as explained earlier. This reduces the ratio of the countershaft occupying the axial length of the entire device, thus making compact the dimension in the axial direction. The adoption of such a configuration involves the placement of a shaft end of the countershaft in-between, which makes it necessary to allow a shaft-to-shaft distance between the generator mounted on an extension of the engine shaft and adjacent to the counter shaft in a radial direction at a similar position in the axial direction, and the electric motor mounted on a different shaft. This results in the dimensions of the radial direction of the entire device, namely the outline in a transverse direction of the shaft, becoming greater.
In the hybrid driving device of the related art, since the parking gear is inserted in a point on the countershaft, the axial length of the countershaft is prevented from being shortened for the length of the parking gear. As a result, compactness achieved through overlap in the axial direction of the rear end of the countershaft and the motor coil end is not sufficiently exploited.
The invention provides a hybrid driving device wherein a driving connection is established between an engine and an electric motor via a countershaft to wheels, to solve the above problem and to enhance the compactness of the device as a whole in an axial direction and a radial direction.
To achieve the foregoing, a hybrid driving device according to this invention is provided with an engine, a first electric motor placed on the same shaft as the engine, an output member placed on the same shaft as, and having a driving connection with, the engine and the first electric motor, a countershaft that is paralleled with the shaft and establishes for the output member a driving connection to wheels, and a parking mechanism that restricts rotation of the wheels. The hybrid driving device is characterized in that a parking gear of the parking mechanism is placed on the output member.
In the configuration according to a first exemplary aspect of this invention, since the parking gear is placed at a portion with a smaller torque amplification on an upstream side along a stream of power transmission as compared with the conventional configuration in which the parking gear is placed on the countershaft, it is possible to reduce the torque applied to the parking mechanism that restricts rotation of the parking gear, which allows the parking gear and other parking mechanism-related parts to be built compact.
The hybrid driving device according to this invention is provided with an engine, a second electric motor placed on a shaft different from that of the engine, an output member placed on the same shaft as, and having a driving connection with, the engine, a countershaft that is paralleled with the shaft and establishes for the output member a driving connection to wheels, and a parking mechanism that restricts rotation of the wheels. The hybrid driving device is characterized in that the countershaft is placed between the engine and the second electric motor in an axial direction and that a parking gear of the parking mechanism is placed on the output member.
In the configuration according to a second exemplary aspect of this invention, in addition to the above-mentioned advantage, it is not necessary to secure an axial length needed to place the parking gear on the countershaft, which makes it possible to shorten the axial length of the countershaft and eventually the overall length of the driving device. Furthermore, the countershaft does not overlap with the second electric motor mounted on a shaft different from the engine shaft in the axial direction. This allows the engine shaft to be brought as close as possible to the second electric motor shaft, which in turn makes it possible to keep small the dimension of the driving device in the radial direction.
If a differential device that transmits rotation of the countershaft to wheels is provided in either one of the above-mentioned configurations, it is effective to organize a configuration in which the countershaft transmits rotations of at least two shafts among an output member shaft, a second electric motor shaft, and a differential device shaft.
In the configuration according to another exemplary aspect of this invention, the same advantages as explained above can be obtained if the driving device is provided with a differential device that transmits rotation of the countershaft to wheels.
If the configuration is provided with a planetary gear that connects the engine and the first electric motor, it is effective to organize a configuration in which the parking gear is formed on an outer periphery of a ring gear of the planetary gear connected to the output member.
In the configuration according to another exemplary aspect of this invention, since the axial length can be reduced for the width of the parking gear in an arrangement in which the parking gear is placed on the output member, the overall length of the driving device in the axial direction can be further shortened.
In the above-mentioned configuration, it is effective to organize a configuration in which the output member is formed by a counter drive gear on the engine side, a first wall that supports the counter drive gear on the engine side provided between the counter drive gear on the engine side and the first electric motor, and a parking pole of the parking mechanism placed on the first wall.
In the configuration according to still another exemplary aspect of this invention, there is no need to provide a special member for placing the parking pole. Therefore the number of parts used and cost can be reduced and, at the same time, the space can be effectively utilized to build a compact driving device.
If a first electric motor is further placed on the same shaft as the engine in the configuration provided with the second electric motor, it is effective to organize a configuration in which the output member is formed by a counter drive gear on the engine side, a first wall that supports the counter drive gear on the engine side provided between the counter drive gear on the engine side and the first electric motor, and a parking pole of the parking mechanism placed in the first wall.
With the configuration according to yet another exemplary aspect of this invention, in the driving device provided with a first electric motor and a second electric motor, it is not necessary to provide a special member for placing the parking pole as described above, thereby reducing the number of parts used and cost and, at the same time, the space can be effectively utilized to build the driving device compact.
If a valve body is provided with a built-in oil pump in any of the above-mentioned configurations, it is also effective to organize a configuration in which parking mechanism-related parts are placed on a side opposite to the engine in an axial direction with respect to the valve body.
In the configuration according to another exemplary aspect of this invention, a bottom portion of the valve body with a built-in oil pump forms an oil sump having a relatively wide area. By placing parking mechanism-related parts in a dead space formed on a side opposite to the engine in the axial direction with respect to the valve body, effective use of space can be made based on the placement of parts not requiring special spaces for placement.
It is further possible to provide, in a configuration where a second wall forms in cooperation with the first wall, a planetary gear chamber accommodating the planetary gear, and an opening that permits engagement between the parking pole and the parking gear formed in the second wall.
In the configuration according to yet another exemplary aspect of this invention, by forming the parking gear on the ring gear of the planetary gear housed in the planetary gear chamber, the engagement of the parking pole with the parking gear through the second wall is made possible without reducing a gear supporting strength of the second wall that encloses the planetary gear accommodating chamber.
It is still further possible to allow a configuration in which the countershaft mutually connects the counter drive gear on the engine side forming the output member, a counter drive gear on the electric motor side provided on the shaft of the second electric motor, and the differential device, thereby transmitting rotation among three shafts of the output member shaft, the second electric motor shaft, and the differential device shaft.
In the configuration according to still another exemplary aspect of this invention, advantages can be obtained of making parking mechanism-related parts more compact, shortening the overall length of the driving device, and providing smaller dimensions in the radial direction based on synergistic effects of each of the above-mentioned advantages.